The Eaton Democrat. (Eaton, Ohio) 1875-1903, 1887-05-05


tho eye. In man and ONE of
his nearest allies, this function is per-
formed by winking the eyelids, and
there is no necessity for any further as
sistance from a third eyelid. In the
same way it is unnecessary in the in
habitants of the waters. 1t is there
fore absent In the great whale family
and in all fshes-the ocean, the river,
or the lake supplying the necessary 10
ton. But there is more than the alb
sence of this wonderful nictitating
membrane to notice in the eyes Of
fishes, for they have no true eyelids at
all. Skin of q structure sufficiently
transparent to allow of the passage of
the rays Of light passes over the eye,
and thus obviates the necessity for
even eyelids. In some cases, as in an
eel, a special protection to the eye is
found-the eel has to work its head
through hard, rough substances such
as gravel and sand. To defend the eye
from injury, therefore, a transparent,
horny, convex case is placed be-
fore the eye in such a n as
10 defend the organ without imped-
ing the sight another wonder
full instance of design. The con-
trivances for the protection Of the eyes
in the different branches of the animal
world are indeed a constant marvel to
the thoughtful. The ~nictitating mem
brane is the most conspicuous, and
forms q contrast to the singular and
unique arrangement which exists only
in the chameleon. Instead of two eye
lids the organ is covered by an eyelid
with q hole in it, and for an obvi-
GUS reason. The neck of the chame-
leon is inflexible, and to make up for
this, the eye is SO prominent that more
than half the ball projects from the
head, the muscle being such that the
pupil of the eye can be carried in every
direction. To defend and lubricate
the globe of an eye so unusually ex-
posed. a special continuance was neces-
sary, hence the pierced lid-the lid
itself keeping the principal part of the
surface of the eye under cover and in a
due state of humidity without a con-
slant Meditation, and the aperture al
lowing the necessary admission of
light.
The position of the eyes on the head,
varying, as it does, the lower we de-
scend in the animal world, affords fur
ther food for reflection. In birds and
the higher animals, the position is uni
form, and obviously most beautiful,
symmetrical, and useful; but in fishes
and insects we find an endless variety
as to position, direction and dimensions.
In some fishes, the eyes have an up
ward aspect. and are very close to-
gether; in others, they are at the side,
and so wide apart as to be slightly
downward in direction; whilst in soles.
turbots. founders and others of the
same family, the eyes are placed, as it
were, one above the other, and both
upon the same side of the head. Some
have enormously large eyes; others are
20 small a to be scarcely visible; and
others, again, SO rudimentary as to be
merely q minute fold of the skin on
which q cerebral nerve terminates.
Generally speaking, however. the eye of
fishes is large, with especially broad open
pupils; and the crystalline lens much
rounder than in the eyes of terrestrial
animals-another proof of design, evil
IDENTIFY intended to enable them to col
ctwhatever rays of light penetrate to
the hidden depths Of the ocean, refrac-
ton of rays of light by a more convex
surface being . necessity from water
into the eye. But of all fishes, the
anableps has perhaps the most note
worthy eye. The creature swims half
above the surface Of the water, and the
eye is divided horizontally into two
portions, the one for seeing in the
water, the other in the air. Insects,
again. are provided with the most won
derful organs of sight. Their nature
and construction are different from all
others, and two kinds of eyes, the SIM
pie and the composite, are united in
one small creature. The simple eyes
are generally three, and are situated on
the crown of the head between the
more elaborate organs of sight. The
structure Of each kind is perfectly
distinct. The composite eyes are
a marvellous combination Of a null
tiplicity Of perfect eyes, which
may be seen in a microscopic
examination of the ornea The cornea
then stands revealed as a mass of many
thousand regularly disposed hexagonal
facets, each of which is in itself a per
feet eye. In the head of a butterfly,
nearly thirty-five thousand have been
counted; and some insects are suppos-
ed to be still more numerously sup
piled. The simple eyes, on the other
hand, are simple, as their name inn
plies; each simple eye is a single organ
the r exhibiting no appearance Of
facets. The uses of these eyes, which
the ~unwearying researches of natural
lists have now established, are as inter-
esting as they r extraordinary.
Reaumur. in his well-known expert.
ments. first smeared the com.
pound eyes of insects with
paint, and next the simple
eyes; and discovered that the COM
pound eyes for horizontal sight, and
the simple for vertical; since those
whose compound eyes were closed
few straight up into the air until they
were lost to sight, and those whose
simple eyes were operated upon winged
their way on all sides amongst the
flowers around, but neither assembled
into the air nor few far away. Com.
pound eyes, in addition, are supposed,
and with good reason, to have the
power of magnifying; and a comical
story is recorded of Puget adjusting
the eye of a flea in such a way as to see
objects through it, and finding that 9
soldier appeared like an army of pig
mics, for what it multiplied it dimin'
ished; and the flame of a candle seem
ed the illumination of a thousand fairy
lamps.